This invention relates to the field of ornithopters which develop lift and thrust through vertical movement of the wings to develop high aerodynamic propulsive efficiency. Further, the invention includes provision for damping the vibration resulting from movement of the wings.
1. Background of the Invention
There is a long history of aerial vehicles which attain flight through the movement of the wings. Of course, the most successful derivation of this concept is the helicopter. Modern helicopters and conventional aircraft have comparable characteristics of speed, lifting capacity and passenger comfort. These characteristics of the helicopter result from the rotary wing design wherein the wings or blades rotate in a plane parallel with the longitudinal axis of the fuselage.
In attaining the level of performance of current models, the helicopter has become a very complex machine requiring highly trained pilots. One of the most notable features of the helicopter is the balancing of dynamic rotational forces to attain controllable flight. The torque generated by the rotary wing acting against the fuselage must be managed by the pilot to attain straight and level flight. In addition, the pilot must simultaneously manipulate other flight controls similar to an airplane. Further, if the helicopter loses the function of the vertical tail rotor or ducted fan, which provides critical anti-rotational force, controlled flight is impossible.
Ornithopters also use a wing drive for flight. In contrast to the rotary wing of the helicopter, the ornithopter has reciprocating wings which move in a plane normal to the longitudinal axis of the fuselage. The ornithopter eliminates the complexity required for overcoming dynamic rotational forces of flight at the expense of flight speed and incidence of reciprocal vibration. However, the lifting capacity of the ornithopter can be substantial and flight operation is less complex than a helicopter.
Because of the reciprocating movement of the wings, ornithopters suffer from harmonic vibration. The power input and resulting differential moments result in vibratory accelerations in the vertical plane. These vibrations are translated to the fuselage and payload unless damped out or reduced in some manner.
Ornithopters can be useful in specialized tasks requiring slow moving observation or lifting or remote flight found in construction, forestry, oil and gas industry, and the military.
2. Description of the Prior Art
U.S. Pat. No. 6,206,324 to Smith discloses an ornithopter with multiple sets of computer controlled wings which may be programmed to reciprocate in various combinations. The angle of attack of the wings is controlled throughout each reciprocation to provide optimal lift and minimal drag.
The Michelson patent, U.S. Pat. No. 6,082,671, is an attempt to teach the concept of a mechanical insect. The wings are twisted, to optimize lift, during reciprocation by rotation of the wing spar.
A toy ornithopter is disclosed in U.S. Pat. No. 4,155,195. The two sets of wings of the device are mounted on the fuselage in a vertically overlapping design. The sets of wings are reciprocated by crank arms oriented at 90 degrees to each other and powered by a rubber band. The sets of wings reciprocate out of phase with each other in that as one set moves downwardly the other set is moving upwardly. The flight path is preset by adjusting the empennage before flight.
What the prior art lacks is an ornithopter with a simple system for damping vibrations resulting from power inputs.
Accordingly, it is an objective of the instant invention to teach an ornithopter having vertically moving wings for developing lift and thrust and a movable tail for directional control.
It is a further objective of the instant invention to teach the use of a vibration damping system to reduce vibration in the fuselage and cockpit or load carrying compartment.
It is yet another objective of the instant invention to teach damping vertical vibration by counterbalancing the forces generated by the wings by a fully articulating empennage.
It is a still further objective of the invention to teach the vibratory isolation of the payload compartment from the wing section.
It is another objective to teach the controllability of the vehicle at slow speeds, well below stall speed of fixed wing aircraft and below the speed at which a conventional empennage is effective, by moving the center of gravity in flight.
It is another objective of the invention to teach that the force required to support the lift of the front set of wings is counterbalanced by the force of the aft set of wings and directional control is affected by controlling the shape and angle of attack of the wings.
Other objects and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings wherein are set forth, by way of illustration and example, certain embodiments of this invention. The drawings constitute a part of this specification and include exemplary embodiments of the present invention and illustrate various objects and features thereof.